(Oregon Coast) - A high surf advisory is in effect from 9 p.m. tonight to 1 p.m. on Wednesday for the Oregon coast, with swells around 18 to 20 feet but combined seas somewhat higher. The National Weather Service (NWS) in Portland issued the advisory, saying the highest waves will wallop the beaches in the overnight hours where waves as high as 25 feet are possible.

The advisory is cause for much caution on the beaches, but not just on Wednesday morning. Sizable waves will continue through Monday as combined seas will stick around 16 feet – although there is no official warning about waves this size.

West-northwest swells of 18 to 20 feet will be hitting the coastline starting later tonight, putting the advisory in effect from the southern Washington coast all the way down to the middle of the Oregon coast, around Florence. It includes all of the upper half of Oregon, such as Seaside, Manzanita, Oceanside, Lincoln City, Newport and Yachats.

“Breaking waves will run up beaches much higher than normal,” the NWS said. “Waves will likely break over jetties much closer to shore than normal. Large driftwood logs will likely roll under the high surf with injuries or death possible to those near on the logs.”

Rip currents will also be of a greater danger during these periods of high wave height, the NWS said.

Other areas to watch out for are the rocky ledges of spots like Yachats or Depoe Bay. Stay well back away from those and stick to parking lots and viewing areas, which will still provide an excellent show.

The beaches will be safer for walking during the rest of the week's rollicking wave action, but stay clear of them during high tides – especially smaller beaches with cliffs close by, such as Oceanside, Gleneden Beach, Newport's Nye Beach and parts of Lincoln City.

Wednesday will be mostly cloudy with some sun breaks and a fair amount of rain. Thursday will be cloudy with lots of downpours. Friday and Saturday look to be mostly cloudy with periods of rain likely, but Monday and Tuesday clear up with partially sunny conditions, even as the waves still put on a show. See full Oregon Coast Weather, Tides here.